public class NewsListActivity extends Activity {
  private List<News> list;
  private ListView listView;
  private LoadImageAdapter adapter;//适配器
  private ACache acache;//缓存框架
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    super.setContentView(R.layout.load_img_listview_activity);
    acache=ACache.get(this);//创建ACache组件
    initView();//初始化界面，代码不贴了
}


public void loadData(){
   String cacheData=acache.getAsString("newsList");//从缓存中取数据
   if(cacheData!=null){//如果缓存中有，就不访问网络
   List<News> newsList=gson.fromJson(cacheData, new TypeToken<List<News>>(){}.getType());//将json转为List
      list.addAll(newsList);
      adapter.notifyDataSetChanged();
      return;
   }
   new Thread(new Runnable() {
     @Override
     public void run() {
       // TODO Auto-generated method stub
       SystemClock.sleep(2000);//模拟网络耗时
       String json=request();//模拟从网络中获取json数据
       acache.put("newslist", json, 60*60*1);//将数据存入缓存中，有效时间设置为1小时
       List<News> newsList=gson.fromJson(json, new TypeToken<List<News>>(){}.getType());
       list.addAll(newsList);
       handler.sendEmptyMessage(1);
    }
         
  }).start();
}
    /**
     * 模拟网络请求方法
     * @return json数据
     */
private String request(){
   News news=null;
   for(int i=0;i<10;i++){
       news=new News();
       news.setId(i);
       news.setImgUrl("course/img/face_"+i+".png");
       news.setTitle("新闻标题"+i);
       news.setSummary("测试"+i);
       list.add(news);
   }
   Gson gson=new Gson();
   return gson.toJson(list);    
}


private Handler handler=new Handler()
   @Override
   public void handleMessage(Message msg) {
       // TODO Auto-generated method stub
       switch(msg.what){
           case 1:
             notify_layout.setVisibility(View.GONE);
             adapter.notifyDataSetChanged();
           break;
       }
   }
}